Emory River Ash Pond Site
KEMRON was contracted to perform a dewatering study for coal ash from the Emory River Ash Pond Site. The objectives of the treatability study included: 1) evaluate the potential for dewatering of the site material (Ash slurry), 2) provide information for users of the study to determine the scale of operation required, 3) evaluate filtration effectiveness of free liquids removed from the site material, and 4) evaluate the handling characteristics of the site materials.
All treatments performed during the treatability study were based on discussions with the client and KEMRON’s experience treating similar types of sludges. After initially characterizing the moisture content, bulk density to confirm the ash slurry represented the ash at the site, The ash slurry provided to KEMRON already contained a treatment of 2% polymer. Therefore, KEMRON proceeded to the Treated Dewatering Evaluation phase of testing. Filter press testing was performed to evaluate the reduction in moisture content that can be achieved by the application of a positive pressure to the untreated ash material. Bench-scale testing was performed at a positive pressure of 150 pounds per square inch (psi) using a Baroid filter press apparatus designed to simulate a plate and frame filter press.
KEMRON generated a 20 % solids ash slurry using site groundwater ratio and used three filter media in the preliminary evaluation. The filtering medium was a coarse grade filter paper with a pore size of 40 micron (um), 20 to 25 um, and 10 um. Filter press testing was performed at a positive pressure of 150 pounds per square inch. The time to reach breakthrough (either no water drained or air blew through drainage) was recorded. Each filter cake was then removed, weighed, measured, and subjected to moisture content testing, bulk density testing, and subjective visual and manual handling evaluation. The objective of the handling evaluation was to determine if the material can be handled by heavy duty machinery and/or stacked.
Based on the results of evaluation, the use of filter press technology was effective in reducing the ash slurry to a relatively dry material which can be stacked, loaded, and transported.
study revealed that the use of a 20 to 25 um filter media and a 40 um filter media increased the 20 % solids ash slurry to an approximate 80 % solids material, with no free liquid. The percent solids of the filtrate significantly increased from 0.88 % to 5.5 % in the 20 to 25 um and 40 um samples, respectively.